Request for an ADAMHA RSA. There has been considerable concern that diets high in refined carbohydrates promote human disease and obesity. Laboratory research has documented that high carbohydrate diets increase caloric intake, body weight, and body fat in animals, but the mechanisms responsible for these effects are not completely understood. New findings from my laboratory have revealed further complexity in carbohydrate appetite. First, we discovered that rats and other species have a taste and appetite for starch-derived polysaccharides distinct from their taste for sugars. Second, we demonstrated that the postingestive actions of carbohydrate can condition extremely strong flavor preferences even for normally avoided tastes (bitter, sour). The goal of this proposal is to further elucidate the postingestive conditioning of appetite by carbohydrates and to assess the impact of carbohydrate taste and conditioning on long-term energy balance. The specific aims of the project are to (1) Evaluate the nutritive unconditioned stimulus (US) in carbohydrate appetite conditioning. The effect of carbohydrate type, concentration, and rate of infusion on conditioning will be determined. (2) Determine the site(s) and route(s) of action of the carbohydrate US. Gastric, intestinal, and hepatic sites, and neural and neural and hormonal routes will be investigated. (3) Evaluate the orosensory conditioned stimulus (CS) in carbohydrate conditioning. The role of olfactory and gustatory cures, and CS palatability in carbohydrate conditioning will be determined. (4) Investigate the behavioral and physiological processes associated with carbohydrate conditioning. Conditioning effects on ingestive patterns, the cephalic insulin response, and central neural coding of taste will be investigated. Also, carbohydrate conditioning and protein conditioning will be compared as will flavor-flavor and flavor-nutrient conditioning. (5) Determine the influence of carbohydrate taste and conditioning on long-term caloric intake, body weight and adiposity. This research will provide new information on the interaction of taste, nutrition and learning in the control of food selection, caloric intake, and body weight. The integration of the research findings from this project with the extensive literature on learning and reinforcement processes and human feeding behavior will be facilitated through extensive reading and study, participation in specialized conferences and seminars, and interaction with experts in these areas.